Gear pump structure



Jam 5 1948. E. s. wrrcHGER 2,434,135 j GEAR PUIP STRUCTURE A Filed nec. 2, 1942 INVEN? 0R f2 I BY Eugene S. l4/z'fcger. l l A 74W l g g y Allokxms.

Patented Jan. 6, 1948 UNITED STATES PATENT OFFICE GEAR PUBD STRUCTURE Eugene S. Witchger, Grosse Pointe Woods, Mich., assignor to Eaton Manufacturng Company, Cleveland, Ohio, a corporation of Ohio Application December 2, 1942, Serial No. 467,564

n 2 Claims. (Cl. 10S-126) vthe provision of a pump of the type described particularly adapted for supplying fuel under pressure to internal combustion engines; and the provision of a pump of the type described in which the by-passing of excess uid between the discharge and intake sides of the Vpump is accomplished in a simple, accurate and efficient manner.

Other objects of the invention include the provision of a rotating positive displacement type of pump including inner and outer gear-like elements rotating in a surrounding casing and in which the outer gear element is provided with an end wall xed thereto and closing the same and which with the outer gear element is bodily movable axially thereof in response to variations in pressure on the discharge side of the pump to maintain the "discharge pressure substantially constant; the provision f a pump of the type described in which the outer gear-like element and its -end wall closure are movable axially as a unit relative to the inner gear-like elements;` the provision of a pump of the type described in which spring means are provided for constantly urging the outer gear-like element and its associated Aend wall closure toward a position in which the inner and outer gear-like elements are transversely aligned with each other; the provision of a pump structure as above described in which the driving force to the gear-likeelement is transmitted to the end wall closure for the outer gear-like element and through it to such gear-like element; the provision of a structure as above described in which the outer gear-like element is substantially free of peripheral contact with its surrounding housing; the provision of a novel driving connection for the shaft of a pump qf the above described construction; and the provision of a pump structure of the type described that is simple in construction, efficient in operation and relatively economical to maufactre.

The above being among the objects of the present invention the same consists in certain novel features of construction and combinations of charge pressure of the pump;

parts to be hereinafter descrlbed'with reference to" the accompanying drawing, and then claimed, having the above and other objects in view, Y

, In the accompanying drawing which illustrates suitable embodiments of the present invention and in which like numerals referto likejparts throughout the several different views,

Fig. 1 is a vertical sectional view taken axially through a rotary pump constructed invaccordance with the present invention and with the various parts shown in their "at rest position;

Fig. 2` is la vertical sectional view taken transversely of the pump shown in Fig. l as on the line 2--2 thereof;

Fig. 3 is a vertical sectional view taken transversely of the pump shown in Fig. 1 as on the line 3-3 thereof;

Fig. 4 is a fragmentary view taken in the same plane as in Fig. 1 and illustrating the position of the outer rotor andy its closure. plate when it has been retracted under the force of the dis- Fig. 5 is a view similar to Fig. 4 but illustrating a modified manner of mounting the outer rotor andits end closure, and a modified arrangement of spring means for constantly urging these in one direction axially thereof; and, g

Fig. 6 is a fragmentary, vertical sectional view taken axially through a modied form of rotary pump constructed in accordance with the present invention. .A

In the broader aspects of the present invention it is capable of use in connection with Various types of rotatable pumps which include internal and external cooperating gear-like elements and the claims are to be interpreted accordingly. The invention =is, however, particularly adapted for use in connection with those types of positive displacement rotary pumps illustrated in U. S. Patent No. 1,682,563, issued August 28, 1928 to Myron F. Hill on Internal'rotor, and accordingly, such type of structure is illustrated in the drawing by way of explanation.l Accordingly, in the pump shown in the drawing and particularly in Figs. 1

to 5, inclusive, there iis an inner rotor 20 and an outer rotor 22, each of these rotors having toothlike projections 24 and 16, respectively, which teeth intermesh with one another.

brought out in Fig. 2 the inner rotor is mounted As bestA V tional practice.

another and a tooth of one substantially completely illls the space between apair of adjacent teeth of the other. "The outer rotor has one more \tooth 26 than the number of teeth 24 of the-inner -another and then approach one another `during each revolution of the rotor to provide variable volume chambers through which the pumping effect is obtained. V

In the construction illustratedin Figs. 1 to 5,

inclusivethe housing for the pump comprises ai main body portion 28 in theV form of a casting having a flat righthand face 36 against which both the inner and outer rotors and 22 substantially contact when the pump is at rest and onto which face open the intakepir and clischarge or exhaust port 34, these ports being connected by threaded openings or passages 3,6 and 38, respectively, to the exteriorof the main body portion 28 and which threaded openings are adapted to receive the threaded ends of pipes, tubes, or fittings inl accordance with conven- As best illustrated in Fig. 3- the intake andexhaust ports 32 and 34 are of ap- I proxlmately semi-circular conformation extending from-points in relatively close proximity to each other atthat side of. the -pump wherethe teeth of the rotors 28and 22. are in full engagement with each-other ,and-1 are spaced from one another by a relatively greater distanceat the opposite side of the pump where the. teeth on the rotors are at their' point of minimum engage-.- ment with each other.

Projecting outwardly to therlght, as Viewed inr shown asformed'integrallytherewitn The inner rotor 20: is rotatably received upon the boss 40 and while it may rotate directly thereon, preferably the boss 40 is provided with a surrounding bushing 42 upon which the inner rotor 26 is actually rotatably mounted. f

Fig. 1 is provided with a plane inner or lefthand -face which lies perpendicular to the axis of the shaft 46 and it is concentric with such axis. The other marginal portion of the 'plate member 48 overlaps theouter or righthand end face of the o'uterrotor 22 and is rigidly fixed thereto as by means of screws 5D in concentric relation to the shaft 46.A The outer rotor 22 is thus fixed to the plate member 48 and, therefore, the shaft 46 for equal rotation and axial movement therewith.

The pump housing includes a more or less cupshaped ap or cover member 6l] in which the rotors 20 d 22 are received in `freely spaced relation to the interiork walls thereof, the open end of the cover 68 beingsecured in sealedrelation with respect to the cooperating face of the main body portion 28, preferably with the inter\ position of a gasket such as 62, by means ofscrews 64 best shown in Fig. 2 and which extend through radially outwardly projecting feet or flanges 66 on the cap or cover member 60.

The end Wall of the cap or cover member 68 ls formed with a hollow longitudinal projection 10 in turn interiorly provided with a hollow inwardly projecting boss 12. Loosely received in the hollow boss 12 for guiding movement in the direction of the axis of the shaft 46 is astem 14 formed integrally and concentrically with re-k spect to a disc 16 located between the inner end of the boss 1'2 and the plate member 48. A coil spring 18 surrounding the boss 12 is maintained under compression between the end wall of the projection 18 and the disc 16. Between the disc 16 and the plate member 48 is a hollow anti-friction washer or thrust member 88 which serves to transmit the force of the spring 18 to the plate member 48. A pin 82 fixed in the disc 16 and projecting axially to the left therefrom as viewed The main body portion 28 and the boss 40 are provided with an opening 44 therein arranged with its axis perpendicular to the plane of the face 30 of. the main body portion 28 and offset from the axis of the'boss 48 by the amount of eccentriclty required between the rotors 20 and 22 for proper interengagement thereof. This eccentricity is particularly well brought out in Figs. 2 and 3. The opening 44 rotatably and axially slidably receives therein a shaft 46 which projects out beyond the end of the boss 40 and there supports a disc-likeplate member 48 preferably of the same diameter as the outerrotor 22 as shown. According to the constructions illustrated in Figs. 1 to 5, inclusive, the plate member4 48 may be either fixed to the shaft 46 or simply secured against relative rotation with respect thereto, for instance, in the manner illustrated in Fig. 5 which will be described in detail later. but as a matter of illustration in the construction shown in Figs. 1 to 4, i lusive, the plate member 48 is formed integrall with or is rigidly fixed to the shaft 46. 'I'he plate member 48 as illustrated in in Fig. 1 is loosely received in the central aperture in the thrust member and loosely projects into `the axial recess 84 provided centrally in the plate member 48. The pin 82 thus serves to maintain the thrust member 80 against material lateral displacement from its intended central position on the plate member 48.

The righthand end of the spring 18 as viewed in Fig. 1 -is preferably sufliciently enlarged in diameter that its end coil is frictionally locked in the, bottom `of the projection 1U, and its outer endis frictionally gripped about the inner portion of `the radially' offset peripheral edge of the disc 16, thereby serving as a means for preventing rotation of the disc' 16 with the plate member 48A during operation of the pump. The force of the spring 18', as will be appreciated more clearly after the following explanation, serves to control the maximum pressure which is built up on the discharge side ofthe pump.

All of the space between the cap or cover member 60 and the unit comprising the plate member 48 and the outer rotor 22, is in constant open communication with the suction port 32 by means of a groove or passage formed in the inner wall of the cap or cover member 60 in line with the suction port 32 and which passage, as best brought out in Fig. 1, is connected by a supplementary passage 92 in the main body portion 28 with the intake port 32. By this means the suction pressure in the pump is at all times exerted on the righthand face of the plate member 48 as viewed in Fig. 1 and where such suction pressure is atmospheric or` substantially so, such pressure thus exists on the back face of the plate member 48.

In operation it will, of course, be appreciated teeth 24 and 26 ofthe rotors Von the suction side of the pump thereby to draw liquid from the port 32 into such chambers, andk such chambers are g closed on the discharge side of the'pump thus to i force the liquid therein out `into the discharge port 34.

\When the pressure of the liquid on the dis-- charge side of the 'p p acting -on the exposed lefthand edges of the outer rotor 22 and -theexposed lefthand face of the plate member -48 is.. sufficiently great to overcome the force of the j cordance with the present invention when the plate member 48 moves outwardly under the influence of increased pressurev on the discharge side of the pump the outer rotor 22 moves with it L and in moving away from the face 30 provides a direct path-of flow for thev excess fluid between the discharge vand intake ports without requiring suchexcess fluid to pass between the teeth of the rotor.

.No increased frictional resistance tothe flow of such fluid is, therefore, exerted'as above explained in connection with previous. designs and it is,

spring 18, the outer rotor 22 and the plate mem -ber 48, together with the shaft 46, move bodily to the right as viewed in Fig. 1 against the force of the spring 18 to a position such as that shown in Fig. 4, for instance. The inner rotor 20 may or may not' move with the outer rotor 22 and the plate member 48, as in the construction illustrated in Figs, 1 to 4, inclusive. it is free to do so. In anyevent when the outer rotor 22. moves to the right with the plate member 48 against the force. of the spring 18. it recedes from the face of the main body portion 28 and, therefore, opens up a therefore, possible with a pump 'designed in ac"- cordance with the present invention to accurately control the, maximum pressure builtv up by the pump withinvery narrowiniits.A

`The shaft 46may, of course, be driven in 'any suitable manner in. accordance with the broader aspects of the' invention. In the particularcase shown the drivingzmeans is formed as follows. The outer endof the opening 44 in which the shaft 46 is rotatably received is diametrically enlarged and its outer end is closed by a gland member or bearing support secured in place by screws. The bearing support 94 interiorly carries abushling 98.l The bushing 98 rotatably supports therein a short hollow or stub shaft |00 having a-transverse central dividing wall |02 therein.. Between passage 93, shown in Fig. 4 only,v between its left'-\ hand face and the surface 30 directly communicating the discharge port 34 with the inlet port 32,

which passage thus permits a direct flow of fluid between these ports to reduce the discharge pressure of the pump.

It will, of course, be appreciated that in actual practice the pump is designed to deliver the necessary volume of liquid at the desired pressure under the slowest speed at which it will normally be intended to operate. For instance, where it is employed to deliver fuel to the carburetor of an internal combustion engine it 'will be designed so that at the lowest idling speed of the engine it will deliver at least therequired amount of fuel to the carburetor at the desired pressure. Accordingly, at any higher speed of the engine the quantity of the inner endy ofthe bearing support 04 and the bottom of the enlarged portion of the; bore 44 is clamped a suitable-or conventional form of shaft sealing device indicated generallyl at |04. An opening |06 extends between the suction port 32 and the surface'of the shaft 46 inwardly of the seal |04 for the purpose of returning any liquid which escapes along the shaft `46 .from the. innr. end thereof,v tothe suction side of the pump,- and to provide for lubrication 'of the drive shaft with\ out washing outthe bearing seal.

The righthand end of the stub shaft |00 isinteriorly provided with. a bore of polygonal crosssectional configuration, preferably hexagonaha'nd the lefthandv end of the shaft 46 is complemenrtarily formed for axially slidable but non-rotatable reception therein, Thel stub shaft |00 1,8*A

providedwith an annular peripheral flange |08 which abuts the inner axial end of the bushing 98 to thereby limit outward movement of the stub 22 will generally be continuously spaced from the face 30 of the main body portion 28 and will float toward 'and from such face to accommodate thev .in cases wherethe increased volume of fluid de-` livered by the pump because pf increased s peed of rotation thereof is required 'to pass through the rotors themselves in being by-passed between the inlet and outlet sides of the pump, it is substan- 'y tially impossible to maintain a substantially constant discharge pressure over all ranges of speed and particularly at higher speeds, this being occasioned by the friction resisting the flow of such Afluid between the teeth of the two rotors. In actween the shaft- 46 and the stub shaft |00; the

lefthand end of the shaft 46 is provided with a f central blind bore in which a relatively light coil spring |0 is received and maintained under compression between the bllndrend of such bore and the transverse wall |02 of the stub shaft |00,

body portion 2|! is yprovided with a nat lefthand face perpendicular to the axis of the shaft 46 and adapted to. bereceivedin at contacting relationship with respect to-a flat-mounting face on the crankca'se of an internal combustion engine or other part, and this fiat face'is provided with a concentric Ypilot portion |2 adapted to betclosely received in a cooperating opening in Isuch flat' .face of the mounting part.v Also, it will be vappreciated that .thestub shaft I 00 may be connected in any suitable manneito a driving shaft but in 1 the particular construction shown'in Fig. 1`-the lefthand end of the borel in the stub shaft-.100 is internally providedwith axially directed serramovement between these parts to offset any slight?.

misalignment between the shaft 46 and the shaft which drives the shaft section. Preferably some means is provided for preventing relative axial movement between the shaft section ||6 and the stub shaft and in the particular construction 'shown the outer or lefthand end of the stub shaft |00 is peripherally grooved and receives therein a split s'pring ring |20 one side of which is fiattened oif on the chord of the circle of the ring and which projects through a transverse slot |22 cutting through one side of the stub shaft |00 and is received in a peripheral groove in the shaft section ||6 midway between its ends. The outer face of the bearing support 84 is recessed as shown to permit application and removal of the ring |20.

As previously stated it is not necessary, in the broader aspects of the invention,` that the plate member 48 or its equivalent be rigidly fixed to the driving shaft 46 or its equivalent and a construction in which the plate member is not so fixed is illustrated in Fig. which otherwise may be considered identical to the construction shown in Figs. 1 to 4, inclusive. In Fig. 5 the shaft corresponding'to the shaft 46 is illustrated at 46a and the plate member equivalent to the plate member 48 is illustrated at 48a. The same inner and outer rotors and 22 as in the previously described construction may be employed and the plate member 48a is secured to the outer rotor 22 by screws 50a corresponding to the screws 50 of the first described construction. member 48a in this modification is provided with a hub |30 which is slidablyreceived on the shaft 'afinstead of being fixed to it-as in the previous construction. The plate member 48a may be axially slidably but non-rotatably fixed to the shaft 46a in any suitable manner, for instance by a connection similar to that between the shaft 46 and stub shaft 00, or between the shaft 00 and shaft 'section ||6, but in the particular instance shown in Fig. 5 the shaft 46a is provided with a slot |32 extending diametrically therethrough and arranged with its plane of thickness axially of the shaft 46a, and a pin |34 fixed at its opposite ends in the hub |30 projects through the slot |32 and is slidable therein axially of the shaft 46a. The outer or righthand end of the shaft 46a is shown as being provided with a blind opening therein Within the length of which the slot |32 is provided but this is not a necessary feature.

f- The spring 18a which surrounds the shaft 46a and constantly urges the plate member 48a and the outer rotor 22 to the lft as viewed in Fig. 5 and thus serves the same purpose as the spring 18 previously described in controlling the discharge pressure of the pump is, in this case, mounted in a different manner than the spring 18. Instead of abutting the end of the housing as in the case of the spring 18 and thus requiring a thrust washer between it and the cooperating plate member 48a, the spring 18a in this case is maintained under compression between the plate member 48a and a disc-like stop member |36 mounted on the extreme right end he shaft 46a as shown in Fig. 5. The stop ember 36 is .removably secured against outward movement on the shaft 46a by means of a split spring ring |38 received in a complementarily formed peripheral The plate groove in the peripheral surface of the shaft 46a.

In view of the fact that the shaft 46a does not move with the wall member 48a in the modification shown in Fig. 5, it will be appreciated that there is no necessity for providing an axially slidable connectionA between its lefthand end and a stub shaft such as the shaft 00 of the previously described construction. In other words, it will be appreciated that if desired the lefthand end of the shaft 46 may be formed to provide an integral part equivalent to the lefthand end of the stub shaft |00 of the construction shown in the previous views, thus obtaining the same advantage-as in the previous. construction, or it may be otherwise formed.

As also previously mentioned it is not necessary in the broader aspects of the invention that the outer rotor 22 be the driven rotor in all cases and in such case it will not be necessary for the outer rotor and the end wall member xed thereto to be supported by the drive shaft. In the construction illustrated in Fig. 6 the main body portion of the housing indicated at 28h, and which corresponds to the main body portion 28 previously described, is provided with an intake port 32b and an intake passage 36h, equivalent to the port 32 and passage 36 of the first described construction, and an exhaust port 34b`and discharge passage 38h corresponding to the exhaust or discharge port 34 and discharge passage 38 of the first described construction. In this case instead of providing a more or less cup-like closure for the righthand face of the main body portion as in the first described construction, the wall equivalent to the side wall of the cover 60 of the first described construction is in this case formed integrally with the main body portion 28b, as illustrated at 60h, and the open righthand end thereof is closed by a plate-like closure |40, thus forming a closed chamber |42 in which the rotors and associated parts are contained. The 'drive shaft 46h is in this case shown as being rotatably supported inthe housingr 28h by a simple bearing |44 and the inner rotor 2Gb is keyed as at |46 to the righthand end thereof which projects into the chamber 42. The outer rotor 22h in this case peripherally engages the inner surface of the wall 6017 which thus serves to rotatably and axially slidably support it in proper relation to the inner rotor 20b, and its outer or righthand end, as viewed in Fig. 6, is closed by a plate member 48b equivalent to the plate members 48 and 48a previously described, and is secured thereto by means of screws 50h. A coil spring '|8b maintained under compression between the end wall |40 and the plate member 48h, preferably with the inter-position of a suitable thrust Washer |44 and piloted upon a boss |46 formed centrally of the plate 48h, serves the same purpose as the springs 18 and 18a of the previously described constructions. The inner surface of the wall 60h is provided with a groove 90b therein serving to provide free communication between the chamber |42 and the suction port 32h in generally the same manner and for the same purpose as the passage 90 in the first described construction.

It will be appreciated that the construction illustrated in Fig. 6 will function in substantially the same manner as the construction shown in the previous views. In other words, the outer rotor 22h and the plate 48h xed thereto will float axially in the chamber |42 under variations in the pressure of the liquid on4 the discharge side of the pump in opposition to the force of the p1ling 16h to provide a by-pass passage of varylng cross-sectional configuration between the lefthand end of the outer rotor 22h and the housing face 30h extending between the discharge port Nb and the' suction port 32h, with all of the advantages connected with this feature-described above in connection with the first describedconstruction.

Having thus described my invention, what I claim by Letters Patent is:

`What is claimed is:

1. In a rotary pump, in combination, a housing providing a chamber therein having a flat end face, a shaft rotatably and axially slidably mounted in said housing and projecting into said chamber in perpendicular relation to said face, a cup-shaped member in said chamber arranged in concentric relation with respect to said shaft and with its bottom wall iixed to the extremity ofy said shaft in said chamber so as to be axially movable therewith and forming an outer rotor, the open edge of said cup-shaped member being adapted to abut said iiat wall, a cylindrical boss projecting into said chamber from said fiat face in surrounding and eccentric relation with respect to said shaft. a toothed inner rotor concentrically and rotatably mounted on said boss within said cup-shaped member, the side walls of said cup-shaped member being interiorly formed to provide teeth lying in mesh with the teeth of said inner rotor, said housing having an inlet passage and an outlet passage opening onto said fiat wall in the area between said inner rotor and said cup-shaped member on opposite sides of the plane of the axes of rotation of said inner rotor and said outer rotor, said passages opening onto said fiat face as ports elongated in the direction of the circumference of said inner rotor and extending angularly of the axis thereof in excess of 90, and spring means cooperating with the closed end of said cup-shaped member constantly urging the latter toward said flat end face, said spring means being adapted to yield under normal pressures 'built up in said pump whereby to permit said cup-shaped member to recede away from said fiat end face thereby to limit the maximum pressure capable of being built up by said pump.

2. In a rotary pump, in combination, a housing y providing a chamber therein having a fiat end face, a shaft rotatably and axially slidably mounted in said housing and projecting into said chamber in perpendicular rotation to said face, a cupshaped member in said chamber arranged in concentric relation with respect to said shaft and with its bottom wall fixed to the extremity of said shaft in said chamber so as to be axially movable therewith and forming an outer rotor, the open edge of said cup-shaped member being adapted maar to abut said fiat wall, a cylindrical boss project-1 ing into said chamber from said flat face in surrounding and eccentric relation with respect to said shaft, a toothed inner rotor concentrically and rotatably mounted on said boss within mid cup-shaped member, the side walls of said cupshaped member being interiorly formed to provide teeth lying in mesh with the teeth of said inner rotor, said housing having an inlet passage and an outlet passage opening onto said flat wall in the area between said inner rotor and said cup-shaped member Iun opposite sides of the plane of the axes of said inner rotor and said outer rotor, said passages opening onto said flat face as ports elongated in the direction of the circumference of said inner rotor and extending anguslidable means coaxial with said shaft interposed between the inner end of said boss and the closed end of said cup-shaped member, anti-friction means interposed between said axially slidable means and said inner end of said cup-shaped member, and spring means constantly urging said axially slidable means toward said cup-shaped member and said cup-shaped member toward said nat end face, said anti-friction means serving to transmit the force of said spring means from said axially slidable means to said cupshaped member, and said spring means being adapted to yield under normal .pressures built up in said pump whereby to permit said cup-shaped member to recede away from said flat end face thereby to limit the maximum pressure capable of being built up by said pump.

EUGENE S. WITCHGER.

REFERENCES CITED The following references are of record in the file of this patent:

-UNITED STATES PATENTS Hill Aug. 19, 1924 Dinesen Aug. 13, 1929 Horawa Mar. 22, 1932 Jensen Apr. 12, 1932 Petersen Sept. 13, 1932 Sperry Jan. 31, 1933 Nichols Apr. 13, 193'? Peter June 24, 1941 FOREIGN PATENTS Country Date Great Britain July 5, 1933 Germany June 16, 1930 German! Apr, 4. 1931 Number Gause et al July 2, 190'11 

